Hi,
I too am having this problem. I have a very small dimension space (3), and a
lot of vectors (hundreds of millions). Therefore I can't print all to disk (I
receive an OOM error). However, I can print 30 sample points easily, and doing
so showed results similar to you (I "named" my vectors to be the number of
vectors clusterDumper printed in the cluster):
VL-50{n=0 c=[...] r=[]}
Weight : [props - optional]: Point:
1.0: 1 = [...]
1.0: 2 = [...]
...
1.0: 10 = [...]
--> note also radius is blank, whereas the points do have spread in all
dimensions, this happened ONLY with converged clusters.
CL-51{n=4 c=[...] r=[...]}
Weight : [props - optional]: Point:
1.0: 1 = [...]
1.0: 2 = [...]
...
1.0: 6 = [...]
As far as I understand the algorithm, problems which arise due to
dimensionality are convergence problems. Basically, distance between points is
"longer" as dimension increases (volume increases dramatically as dimension
increases).
This shouldn't affect clusterDumper, as clusterDumper simply reports on
sequence files from a completed job. This is why the discrepancy is not making
a lot of sense to me. Having more vectors within each cluster makes sense --
when I sum the printed n values, I receive a number magnitudes smaller than the
number of vectors I clustered.
I used Mahout v0.7, Hadoop 0.20.2-cdh3u3
-----Original Message-----
From: Yuji NISHIDA@U-Tokyo [mailto:[email protected]]
Sent: Sunday, September 09, 2012 4:46 AM
To: [email protected]
Subject: Re: mahout clusterdump output
Hi all
I still want to confirm that this is not a problem.
Especially the n value, I just hope it is not problematic...
I discussed this in my lab, one of our members noted that the dimension of
feature vectors and the number of vectors I used were very different.
I have used 100 dimensions of vector and 600,000 vectors.
Do you think it may cause some problems if I use both small dimensions and
large number of vectors simultaneously and we need to make sure that there
is relation between them (especially in number)?
Or do you think 100 is too small for the dimension?
I will appreciate very much that someone follows my question.
Regards.
2012/8/4 Yuji NISHIDA@U-Tokyo <[email protected]>:
> Dear all
>
> I am working on mahout to use canopy and kmeans and got a problem
> about clusterdump output.
> Each vector has simple number incremented from 1 as its name.
>
> When I used 5,000 vectors, I got a correct output. It looks like:
>
> VL-0{n=64,c=[...], r[...]}
> 1.0: 1= [...]
> 1.0: 3= [...]
> 1.0: 4= [...]
> ...
> 1.0: 396= [...] # The number of vectors is exactly same as n(64).
> VL-1{n=5,c=[...], r[...]}
> 1.0: 2= [...]
> 1.0: 12= [...]
> ...
> 1.0: 4221= [...]
> VL-2{n=121,c=[...], r[...]}
> ...
>
> Each number of vectors in VL is exactly same as its n value.
>
> When I used 600,000 vectors, the output looks wrong like:
>
> VL-0{n=14,c=[...], r[...]}
> 1.0: 66636= [...]
> 1.0: 122570= [...]
> ...
> 1.0: 522794= [...] # The number of vectors is 31.
> VL-8{n=0,c=[...], r[...]}
> 1.0: 393539= [...]
> 1.0: 398877= [...]
> ...
> 1.0: 513448= [...] # The number of vectors is 5.
> VL-16{n=2,c=[...], r[...]}
> ...
>
> It looks VL-1 to VL-7 and VL-9 to VL-15 are not used but I confirmed
> them existing in the output.
> It seems using VL in order as 0,8,16,...,11552, 1,9,17,...,11553,
> 2,10,18... and so on.
>
> Can I believe this result or should I doubt this is caused by some bugs?
>
> Hadoop : 0.20.204
> Mahout : rev. 1351561, 1366995, 1367871
>
> Best regards.
>
> --
> nishidy@u-tokyo
--
nishidy@u-tokyo
